1. Field of the Invention
The present invention relates to a mechanism for controlling a transmission of data messages, in particular of short messages of a short message service (SMS), in a communication network. In particular, the present invention relates to a method of controlling a transmission of data messages to a user equipment (UE) by an external short message gateway entity (SM-GW), a corresponding message gateway entity, a corresponding home subscriber database, such as a Home Location Register (HLR) or Home Subscriber Server (HSS), a corresponding system and a corresponding computer program product, which are usable for controlling a message transmission by providing corresponding routing information which are provided by means of a registration procedure.
For the purpose of the present invention to be described herein below, it should be noted that                a user equipment may for example be any device by means of which a user may access a communication network; this implies mobile as well as non-mobile devices and networks, independent of the technology platform on which they are based; only as an example, it is noted that communication equipments operated according to principles standardized by the 3rd Generation Partnership Project 3GPP and known for example as UMTS terminals are particularly suitable for being used in connection with the present invention;        although reference was made herein before to short messages, this exemplifies only a specific example of message type having a particular content; content as used in the present invention is intended to mean also multimedia data of at least one of audio data, video data, image data, text data, and meta data descriptive of attributes of the audio, video, image and/or text data, any combination thereof or even, alternatively or additionally, other data such as, as a further example, program code of an application program to be accessed/downloaded;        method steps likely to be implemented as software code portions and being run using a processor at one of the entities described herein below are software code independent and can be specified using any known or future developed programming language;        method steps and/or devices likely to be implemented as hardware components at one of the entities are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS, CMOS, BiCMOS, ECL, TTL, etc, using for example ASIC components or DSP components, as an example;        generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention;        devices or means can be implemented as individual devices or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved.        
2. Related Prior Art
In the last years, an increasingly extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) communication networks like the Universal Mobile Telecommunications System (UMTS), cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolutions (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), the International Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), and the like are working on standards for telecommunication network and multiple access environments.
In general, the system structure of a communication network is such that one party, e.g. a subscriber's communication equipment, such as a mobile station, a mobile phone, a fixed phone, a personal computer (PC), a laptop, a personal digital assistant (PDA) or the like, is connected via transceivers and interfaces, such as an air interface, a wired interface or the like, to an access network subsystem. The access network subsystem controls the communication connection to and from the communication equipment and is connected via an interface to a corresponding core or backbone network subsystem. The core (or backbone) network subsystem switches the data transmitted via the communication connection to a destination party, such as another communication equipment, a service provider (server/proxy), or another communication network. It is to be noted that the core network subsystem may be connected to a plurality of access network subsystems. Depending on the used communication network, the actual network structure may vary, as known for those skilled in the art and defined in respective specifications, for example, for UMTS, GSM and the like.
Generally, for properly establishing and handling a communication connection between network elements such as the user equipment (or subscriber terminal) and another communication equipment or terminal, a database, a server, etc., one or more intermediate network elements, such as network control elements, support nodes or service nodes are involved. Network control elements, such as a Mobile Switching Center (MSC), a Serving GPRS Support Node (SGSN) or the like, are responsible for controlling the call establishment, call control, call termination, and the like.
Since more and more communication network systems, such as circuit switched (CS) networks, packet switched (PS) networks, Internet Protocol (IP) based networks, for example IP Multimedia Subsystem (IMS), and the like are established in parallel, the provision of an interconnection between these network systems for enabling the continuation of calls of a subscriber or the exchange of messages like SMS, gets an increased relevance. In this connection, it is necessary to ensure that, for example, message transmissions are routed correctly to a destination.
In the case of a 3GPP based network, such as a 2G or 3G telecommunication network (GSM/UMTS), currently, a transmission of a mobile terminated short message in the corresponding GSM/UMTS core networks is possible only via MSCs or SGSNs for routing of the short message towards a subscriber. Routing information is normally retrieved by the core network elements from a database, such as a HLR or HSS.
There are emerging, however, requirements that the sending of the short message is also possible by using some external (from GSM/UMTS core networks point of view) gateways. An example for such a requirement is presented in the 3GPP specification TS 23.204 (Support of SMS and MMS over generic 3GPP IP access), V1.0.0.
In this document, capabilities and enhancements needed to support SMS over a generic IP Connectivity Access Network (IP-CAN) using IMS capabilities are specified. In particular, there is described to use an IP Short Message Gateway (IP-SM-GW) which provides the protocol interworking for delivery of the short message between an IP-based UE and the Short Message Service Center (SMSC). The functions of this element are to connect to the Gateway MSC (GMSC) wherein it appears to the SMS-GMSC as an MSC or SGSN, to connect to a SMS Interworking MSC (SMS-IWMSC) using established MAP protocols, wherein it appears to the SMS-IWMSC as an MSC or SGSN, to communicate with the UE using IMS messaging as transport while maintaining the format and functionality of the SMS message, to acquire knowledge of the association between the MSISDN and the IP address of the terminal, and to act as an Application Server (AS) towards the IMS core. In order to support such a SMS over generic IP access, the HSS shall support the following functions: storing the address of the IP-SM-GW and providing it as part of a “send routing information for short message” procedure, and an indication that the terminal is registered with an IP-SM-GW for delivery of SMS. In order to be able to return the address of the IP-SM-GW in response to a “SendRoutingInfoForShortMsg” request from the SMS-GMSC, the HSS needs to have an indication that the terminal is registered with an IP Short Message Gateway and that this is the preferred method for delivery of short messages. The IP-SM-GW is informed of the UE's registration status in the IMS. On registration, the IP-SM-GW sends a message to the HSS indicating that the UE has successfully registered.
For the registration or deregistration procedure for the UE and the IP-SM-GW, according to the TS23.204 specification, it is specified to use IP-SM-GW-(De)register Request and IP-SM-GW (De)Register Response over a Sh interface for (de)registration. The Sh interface is provided between the IP-SM-GW and the HSS and allows the HSS to be informed that the user is capable of receiving SMS over IMS. MSC or SGSN addresses are updated in the HLR in connection with a location update or the like.
However, 3GPP standards do not ‘separate’ HLR and HSS. This means that the HSS, according the 3GPP, comprise both functionality sets. In practice, however, it is possible and often the case that HLR and HSS are different network elements. So, if the IP-SM-GW address is sent to HSS via the Sh interface, as defined in the present art, then it is necessary to provide proprietary solution for delivering the address further to HLR. It is to be noted that this address is particularly needed in the HLR. Furthermore, the Sh interface is based on Diameter protocol F and is thus a vendor specific Diameter application. Hence, the network structure can become more complex and thus more expensive.